Gen Dent. 2021 May-Jun;69(3):42-45.
The aim of this study was to compare PETG/TPU (polyethylene terephthalate glycol/thermoplastic polyurethane) with PETG (polyethylene terephthalate glycol), based on color stability and microhardness. Sixty circular specimens (10 mm in diameter × 3 mm thick) were fabricated (30 PETG/TPU and 30 PETG). The specimens in both groups were submitted to 2000 thermal cycles in alternating baths of 60 seconds at 5°C ± 1°C and 55°C ± 1°C. The specimens were then divided into subgroups (n = 10) that were disinfected 15 minutes per day for 60 days in 1 of 3 solutions: liquid soap, 2% chlorhexidine, or Listerine. Color change (∆E*) and Knoop microhardness tests were performed at baseline (T0), after thermocycling (T1), and after disinfection (T2). Analysis of variance (ANOVA) and Tukey test were used (P < 0.05). ANOVA showed that there was no statistically significant difference in color change between the 2 materials after thermocycling (∆E1) or after disinfection (∆E2), regardless of the disinfectant. Intragroup comparisons (Listerine, liquid soap, and 2% chlorhexidine) of the 3 PETG/TPU groups or 3 PETG groups after disinfection revealed no statistically significant difference for microhardness. Comparison of PETG/TPU with PETG based on the overall mean microhardness showed that the PETG/TPU had a significantly greater mean surface hardness value (P < 0.05). The Tukey test revealed statistically significant increases in microhardness at T1 and T2 for PETG/TPU and PETG so that T0 < T1 < T2 (P < 0.05). Both thermoplastic materials demonstrated an increase in hardness after thermocycling and after disinfection, and both showed similar color changes regardless of the disinfection method. Based on the color evaluation, the liquid soap proved to be the best option for disinfection of PETG/TPU and PETG, because the color change (∆E* value) was clinically acceptable for both materials.
本研究旨在比较 PETG/TPU（聚对苯二甲酸乙二醇/热塑性聚氨酯）和 PETG（聚对苯二甲酸乙二醇）在颜色稳定性和显微硬度方面的差异。制备了 60 个圆形试件（直径 10mm，厚 3mm）（30 个 PETG/TPU 和 30 个 PETG）。两组试件均在 5°C±1°C 和 55°C±1°C 的交替水浴中进行 2000 次热循环。然后将试件分为亚组（n=10），每天用 1 种消毒剂消毒 15 分钟，共 60 天，消毒剂包括液体皂、2%洗必泰或李施德林。在基线（T0）、热循环后（T1）和消毒后（T2）分别进行颜色变化（∆E*）和努普显微硬度测试。采用方差分析（ANOVA）和 Tukey 检验（P<0.05）。ANOVA 结果显示，热循环后（∆E1）或消毒后（∆E2），两种材料的颜色变化均无统计学差异，无论使用哪种消毒剂。3 个 PETG/TPU 组或 3 个 PETG 组在消毒后的组内比较（李施德林、液体皂和 2%洗必泰），显微硬度均无统计学差异。基于总体平均显微硬度，将 PETG/TPU 与 PETG 进行比较，发现 PETG/TPU 的平均表面硬度值显著更高（P<0.05）。Tukey 检验显示，PETG/TPU 和 PETG 的显微硬度在 T1 和 T2 时均显著增加，即 T0<T1<T2（P<0.05）。两种热塑性材料在热循环和消毒后均表现出硬度增加，且无论消毒方法如何，颜色变化均相似。基于颜色评估，液体皂被证明是消毒 PETG/TPU 和 PETG 的最佳选择，因为两种材料的颜色变化（∆E*值）均在临床可接受范围内。
